In recent years municipalities have found an increasing use of fire hydrants by unauthorized persons during hot weather, civil disturbances and the like. The unauthorized use causes considerable waste of water which is both costly and dangerous, especially when it taxes reservoirs and there may be a fire and the use of other fire hydrants are handicapped as the water pressure therein may be reduced.
Heretofore, efforts have been made to design tamperproof fire hydrants which required specially designed and manufactured fire hydrants, such hydrants requiring the utilization of special tools attached to operate the hydrants by depressing the valve stems vertically against water pressure to open hydrants. Additional structures have required special operating devices as the operating nut had a peculiarly shaped head. These types of tamperproof hydrants were costly to manufacture and required municipalities to spend a great deal of money replacing existing hydrants.
A second type of tamperproof hydrant utilizing a dome shaped cap to conceal the conventional polygonal end portion of the operating nut and leaving only limited access thereto was designed and required extensive modification of the fire hydrants at the site of use. While this type of tamperproof hydrant left only a limited access space to get at the polygonal end portion, the means for rotatably retaining the dome shaped cap operatively on the polygonal end portion of the operating nut included a modification with a number of parts including rigidly fixing a cylindrical member to the polygonal end portion by bolts. This arrangement was costly and if any of the bolts subsequently backed out of the cylindrical part, they would engage the flange of the dome shaped cap or the retaining ring preventing the cap from being freely rotatable.
An improved type of tamperproof hydrant utilizing a dome shaped cap freely rotatable on the polygonal end portion of the operating nut to provide a limited access space is disclosed in the copending U.S. application Ser. No. 736,830, filed concurrently herewith on May 22, 1985 by Wilbur R. Leopold, Jr. and Dennis Humes and entitled TAMPERPROOF FIRE HYDRANTS. This application has a common assignee, Mueller Co. of Decatur, Ill. and the subject matter of the same is incorporated by reference herein.